Topogràfic
D - World History
80
H - Social Science
62
L - Education
33
K - Law
30
P - Language and Literature
27
T - Technology
20
N - Fine Arts
17
J - Political Science
16
C - Historical Sciences
13
B - Filosofia, Psicologia, Religió
10
G - Geography, Anthropology, Recreation
6
R - Medicine
5
M - Music
3
Q - Science
2
A - Treballs generalss
1
F - General American History
1
S - Agriculture
1
Z - Library Science
1